* basic-block.h (basic_block): Add new field 'flags'.
(BB_REACHABLE): Define.
(expunge_block): Declare.
* flow.c (ENTRY_BLOCK_PTR): Initialize field 'flags'.
(EXIT_BLOCK_PTR): Ditto.
(expunge_block): Remove static declaration.
(cleanup_cfg): Clear bb->aux on every basic block.
(find_unreachable_blocks): Set BB_REACHABLE bit in bb->flags when
computing reachability.
(delete_unreachable_blocks): Delete block b if b->flags has
BB_REACHABLE unset.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@45068
138bc75d-0d04-0410-961f-
82ee72b054a4